We Can Now Wirelessly Power Tiny Electronic Devices Implanted in the Body

Staff Writer

Image: Stanford University

In figuring out how to wirelessly power implantable electronic medical devices, researchers at Stanford University may have just cleared the last remaining hurdle to making the gadgets practical.

Huge advances in nanotechnology have driven down the size of the sensors and components necessary to hack your own body, but the batteries to power them haven't followed suit, making DIY cyborgs look like this:

"With this power transfer method, we can miniaturize the last thing that makes medical devices so large,” John Ho, lead author of a study published in Proceedings of the National Academy of Sciences detailing the research, said in a video explaining it. "We can make it the size of a grain of rice. We can power it anywhere in the body, including the heart or the brain.”

In fact, the technique has already been used to create a working pacemaker in a rabbit that is “several orders of magnitude” smaller than existing ones. Human trials are next, and the tech could quickly jump out of the strictly medical realm and could be used for consumer products like running trackers that are in your hands or legs rather than strapped to your wrist, bluetooth-connected microphones embedded near your vocal cords, and other bionic tech.

The breakthrough comes thanks to the use of what the researchers are calling “midfield powering.” Traditionally, wireless charging has used near field powering, which requires the power source and the thing being powered to be nearly touching, and advances have been made to allow wireless charging further away. Naturally, midfield powering occurs somewhere in between—perfect for having a power source outside the body and a device being powered in, say, your heart.

To make it work, Ho and his team placed a small power "plate" outside the body. The power source sends electricity into the body, and tiny coils inside the implantable device are able to passively receive the power inside, and potentially through the body.

Sound scary? It kind of is. Ho admits that the most dangerous thing about wireless charging is the health risk, but the power plate and associated sensor use about a thousand times less energy than previous designs, which were tissue-specific and could only exist very close to the skin's surface.

The entire thing can fit inside a catheter. Image: PNAS

The team says that the level of power being pulsed through the body is “unlikely to have a meaningful impact on core body temperature” and that it falls within healthy radiation levels.

Already, the tech has been tested successfully in pigs and rabbits—the next step is to try it on humans and to eventually add a battery back into the mix. Yeah, the big breakthrough here is that a battery isn't necessary, but the goal is to create tiny ones that can be recharged as you sleep, so a constant power source isn't necessary at all.

“Future systems may also incorporate a small rechargeable battery to enable continuous operation without an externally worn power source,” Ho wrote. “These capabilities should substantially increase the viability of implanting electronics in living systems.”